Tarifa Anamary, Almirall José R
Department of Chemistry and Biochemistry and International Forensic Research Institute, Florida International University, 11200 SW 8th Street, Miami, FL 33199, USA.
Department of Chemistry and Biochemistry and International Forensic Research Institute, Florida International University, 11200 SW 8th Street, Miami, FL 33199, USA.
Sci Justice. 2015 May;55(3):168-75. doi: 10.1016/j.scijus.2015.02.003. Epub 2015 Mar 13.
A rapid method for the characterization of both organic and inorganic components of gunshot residues (GSR) is proposed as an alternative tool to facilitate the identification of a suspected shooter. In this study, two fast screening methods were developed and optimized for the detection of organic compounds and inorganic components indicative of GSR presence on the hands of shooters and non-shooters. The proposed methods consist of headspace extraction of volatile organic compounds using a capillary microextraction of volatiles (CMV) device previously reported as a high-efficiency sampler followed by detection by GC-MS. This novel sampling technique has the potential to yield fast results (<2min sampling) and high sensitivity capable of detecting 3ng of diphenylamine (DPA) and 8ng of nitroglycerine (NG). Direct analysis of the headspace of over 50 swabs collected from the hands of suspected shooters (and non-shooters) provides information regarding VOCs present on their hands. In addition, a fast laser induced breakdown spectroscopy (LIBS) screening method for the detection of the inorganic components indicative of the presence of GSR (Sb, Pb and Ba) is described. The sampling method for the inorganics consists of liquid extraction of the target elements from the same cotton swabs (previously analyzed for VOCs) and an additional 30 swab samples followed by spiking 1μL of the extract solution onto a Teflon disk and then analyzed by LIBS. Advantages of LIBS include fast analysis (~12s per sample) and high selectivity and sensitivity, with expected LODs 0.1-18ng for each of the target elements after sampling. The analytical performance of the LIBS method is also compared to previously reported methods (inductively coupled plasma-optical emission spectroscopy). The combination of fast CMV sampling, unambiguous organic compound identification with GC-MS and fast LIBS analysis provides the basis for a new comprehensive screening method for GSR.
本文提出了一种快速表征枪击残留物（GSR）有机和无机成分的方法，作为协助识别疑似枪手的替代工具。在本研究中，开发并优化了两种快速筛查方法，用于检测表明枪手和非枪手手上存在GSR的有机化合物和无机成分。所提出的方法包括使用先前报道的高效采样器——毛细管微萃取挥发物（CMV）装置对挥发性有机化合物进行顶空萃取，然后通过气相色谱 - 质谱联用仪（GC-MS）进行检测。这种新型采样技术有可能产生快速结果（采样时间<2分钟），并且具有高灵敏度，能够检测到3纳克的二苯胺（DPA）和8纳克的硝化甘油（NG）。对从疑似枪手（和非枪手）手上采集的50多个拭子的顶空进行直接分析，可提供有关其手上存在的挥发性有机化合物（VOC）的信息。此外，还描述了一种用于检测表明GSR存在的无机成分（锑、铅和钡）的快速激光诱导击穿光谱（LIBS）筛查方法。无机物的采样方法包括从相同的棉签（先前已分析过VOC）以及另外30个棉签样本中对目标元素进行液体萃取，然后将1微升萃取溶液加样到聚四氟乙烯盘上，再通过LIBS进行分析。LIBS的优点包括快速分析（每个样品约12秒）以及高选择性和灵敏度，采样后每种目标元素的预期检测限为0.1 - 18纳克。还将LIBS方法的分析性能与先前报道的方法（电感耦合等离子体发射光谱法）进行了比较。快速CMV采样与GC-MS对有机化合物的明确鉴定以及快速LIBS分析相结合，为一种新的GSR综合筛查方法奠定了基础。
